Continuing studies designed to elucidate the various stages of HIV infection, including virus adsorption, penetration, morphogenesis of new particles and egress from the cell have been carried out using electron-microscopy. Of interest are our EM studies of an HIV mutant in which a major portion of the A gene has been deleted but which is able to produce low levels RT in mass culture. These infected cultures contain a few cells which appear to be dying as they produce large numbers of mature virions while the majority of cells have a few particles on their surface. EM examination of cloned cell populations from such mass cultures demonstrate wide variations in the number and stage of virus particles produced while none of these cultures are able to produce any RT. Current studies of human macrophages exposed to mycobacterium avian (a frequently occurring opportunistic infection in AIDS patients) clearly show that the cells are capable of ingesting large numbers of bacteria but such bacteria are not killed but continue to multiply until the macrophages literally burst. Two divergent field strains of HIV (the NY5 and Alabama strains) have been molecularly cloned and are currently being tested for infectivity. Infectious clones will soon be amplified and used for the production of "type" specific polyclonal antibody in various test animals.